Single phase motors, particularly those in the integral horse power range, typically have lower performance and higher cost than three phase motors. Consequently, where three phase power is available for applications requiring all but the smallest drive motors, three phase motors are typically used. However, many rural areas of the United States are supplied only with single phase AC power. Thus, farms and other agricultural operations which require electric motor drives have commonly been limited to using single phase motors.
Various solutions have been proposed for converting single phase power to three phase power to allow three phase motors to be utilized where only single phase power is available. Some single phase to three phase converters have been available commercially. Nonetheless, the relatively significant additional cost associated with the single phase to three phase converter has limited the widespread use of three phase motors in agricultural applications.